Santosh J. Gharpure

A central strategy for converting natural products into fluorescent probes

A Central Strategy for Converting Natural Products into Fluorescent Probes Matthew D. Alexander, Michael D. Burkart, Michael S. Leonard, Padma Portonovo, Bo Liang, Xiaobin Ding, Madeleine M. Joulli!, Brian M. Gulledge, James B. Aggen, A. Richard Chamberlin, Joel Sandler, William Fenical, Jian Cui, Santosh J. Gharpure, Alexei Polosukhin, Hai-Ren Zhang, P. Andrew Evans, Adam D. Richardson, Mary Kay Harper, Chris M. Ireland, Binh G. Vong, Thomas P. Brady, Emmanuel A. Theodorakis, and James J. La Clair*

Stereoselective synthesis of donor-acceptor substituted cyclopropafuranones by intramolecular cyclopropanation of vinylogous carbonates: divergent synthesis of tetrahydrofuran-3-one, tetrahydropyran-3-one, and lactones.

A new, highly stereoselective intramolecular cyclopropanation of vinylogous carbonate with carbenes using copper catalyst is described. Each of the cyclopropane bonds of these two acceptor substituted cyclopropafuranones can be cleaved with complete regiocontrol by judicious choice of reaction conditions, leading to a diverse array of frameworks such as tetrahydrofuran-3-one, tetrahydropyran-3-one, and lactones.

Tandem alkylation-Michael addition to vinylogous carbonates for the stereoselective construction of 2,3,3,6-tetrasubstituted tetrahydropyrans.

A stereoselective method for the synthesis of substituted tetrahydropyran derivatives employing a tandem S(N)2-Michael addition sequence to vinylogous carbonates is developed. The method is extended to the synthesis of bicyclic ether motifs present in polyether ladder toxins.

Stereoselective Synthesis of Oxa- and Aza-Angular Triquinanes Using Tandem Radical Cyclization to Vinylogous Carbonates and Carbamates

Tandem radical cyclization to vinylogous carbonates and carbamates is developed for a new, highly stereoselective synthesis of heterocyclic angular triquinanes. The strategy is also useful to gain access to oxa- and azatriquinanes, which incorporate the spiroindoline moiety. The method is further extended to the synthesis of lactone-bearing as well as uracil-fused angular triquinanes.

Donor-acceptor substituted cyclopropane to butanolide and butenolide natural products: enantiospecific first total synthesis of (+)-hydroxyancepsenolide.

An oxygen substituted donor-acceptor cyclopropane (DAC) is used as a common intermediate in the enantiospecific collective total synthesis of butanolide- and butenolide-based natural products like (+)-juruenolide C and D, (+)-blastmycinone, (+)-antimycinone, and (+)-ancepsenolide. Enantiospecific first total syntheses of (+)-hydroxyancepsenolide and its acetate are achieved confirming their absolute stereochemistry.

Hetero Diels–Alder reaction of olefin with o-quinone methides generated using (±)-binolphosphoric acid for the stereoselective synthesis of 2,4-diarylbenzopyrans: application to the formal synthesis of myristinin B/C

Hetero Diels–Alder reaction of olefin with o-quinone methides (o-QMs) generated using (±)-binolphosphoric acid was developed for the stereoselective synthesis of 2,4-diarylbenzopyrans. The method thus developed was utilized in the formal synthesis of myristinin B/C.

Tandem SN2-Michael addition to vinylogous carbonates for the stereoselective construction of 2,3,3,5-tetrasubstituted tetrahydrofurans

A stereoselective method for the synthesis of substituted tetrahydrofuran derivatives employing a tandem alkylation-Michael addition sequence to vinylogous carbonates is developed. The method could be used to synthesize THFs bearing tertiary ethers. Further, the method is extended to the synthesis of adjacent bis-THFs.

Stereoselective Synthesis of C-Substituted Morpholine Derivatives using Reductive Etherification Reaction: Total Synthesis of Chelonin C

A general strategy is developed for the stereoselective synthesis of C-substituted morpholine derivatives using intramolecular reductive etherification reaction. The method is extended to the first stereoselective total synthesis of (±)-chelonin C.

Enantiospecific first total synthesis of (−)-4-thiocyanatoneopupukeanane

Abstract The first total synthesis of (−)-4-thiocyanatoneopupukeanane starting from ( R )-carvone has been achieved, establishing the relative as well as absolute structure of the natural product.

Substituted diphenyl butadiynes: a computational study of geometries and electronic transitions using DFT/TD-DFT.

This work is aimed at theoretical understanding of electronic absorption and emission energies of a series of substituted diphenyl butadiynes through an assessment of several TDDFT functionals and a detailed study of solvent effects on their ground and excited state structures and properties. Out of a series of functionals examined, the coulomb attenuated DFT functional CAM-B3LYP is found to be most successful in predicting charge transfer absorption and emission energies of such derivatives. However, TDDFT potential energy surfaces obtained from hybrid functionals such as B3LYP and PBE0 are found to give a good description of the stability of locally excited (LE) and intramolecular charge transfer (ICT) states as a function of torsional angle, for the butadiynyl fluorophores. Interesting structural variations are observed in the ground and excited state optimized geometries of the fluorophores. The ICT emission of the butadiynyl fluorophores is observed to originate from the twisted state where the two phenyl rings in the diphenyl butadiyne get twisted around the butadiyne moiety. A bending of the butadiyne moiety is noted for some of the butadiynyl derivatives in the ICT emissive state. In addition, the direction of absorption and emission transition dipole moment vectors of the butadiynyl fluorophores is found to depend on the nature of substituents present at the periphery of the diphenyl butadiyne moiety.